[doap-interest] On the cardinality of properties

[Damian Steer]

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On 26 Jan 2005, at 23:11, Jorge Santos wrote:

> Hello, I have reviewed the IBM developerWorks articles and the mailing
> list and I couldn't find an answer to this so here it is: wouldn't it
> be a good idea to give a cardinality property
> (http://www.w3.org/TR/2004/REC-owl-guide-20040210/#simpleCardinality)
> to some of the properties defined in the DOAP schema to make some
> fields compulsory.

Strictly speaking cardinality restrictions say things like 'property X 
has a value' not 'property X must have a value'. So it doesn't really 
say what (I think) you want. As a result you don't see it used in RDF 
schemas.

However although OWL restrictions don't do the same job as restrictions 
in XML schema I think this is a good idea. The RSS 1.1 proposal [1] 
does what you suggest. I've also be using OWL for validation-ish tasks 
in a project I'm working on currently, and I've even put in a paper 
covering this topic for XTech. Basically it's useful documentation in 
the schema, and one might even (gently) suggest that those properties 
should have values if they're missing in documents.

Damian

[1] http://inamidst.com/rss1.1/
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